Door latch and interlock

ABSTRACT

A door latch and interlock system particularly adapted for use in connection with laundry equipment including both a door latch and an associated door lock mechanism which is solenoid operated. Separate switches sense the positioning of the lock and latch members, and serve to prevent the machine from being started when the door is not latched, and act as a holding circuit for the push-to-start circuitry.

Umted States Patent 1151 3,673,824

Ripsco et al. July 4, 1972 1541 DOOR LATCH AND INTERLOCK 3,602,015 8/1971 Hughes ..68/l39 [72l Inventors: William B. Ripsco, Coloma' John W. 1

v Pnmary lzxammer-Wflham I. Pnce Blanch stcvcmvlnc' both of Mlch' Attorney-James S. Ncttleton, Thomas E. Turcottc, Donald I73] Assignee: Whirlpool Corporation, Benton Harbor, W. Thomas, Franklin C. Harter, Gene A. Heth, Anthony Mich. Nicwyk and Robert L. Judd [22] Filed: Feb. 23, 1971 [57] ABSTRACT Appl' A door latch and interlock system particularly adapted for use in connection with laundry equipment including both a door [52] U.S.Cl. ..68/l2 R, 68/139 latch and an associated door lock mechanism which is sole- [51] Int. Cl. ..D06f 33/02, D06f 39/14 noid operated. Separate switches sense the positioning of the [58] Field of Search ..68/l2 R, 12 F, 139; 134/57 DL, lock and latch members, and serve to prevent the machine 134/58 DL from being started when the door is not latched, and act as a holding circuit for the push-to-start circuitry. [56] References Cited 6 Claims, 5 Drawing Figures UNITED STATES PATENTS 3,243,977 4/1966 Norgaard ..68/12 R PATENTEDJUL 14mm 3,673,824

sum 10! 2 INVENTORS 7 41/4111 Eye/Paco WM% g ATTORNEYS DOOR LATCH AND INTERLOCK BACKGROUND OF THE INVENTION 1 Field of the Invention This invention is in the field of mechanical and electrical devices for assuring that the door of a laundry appliance is locked at all times and cannot be opened unless power is removed from the machine.

2. Description of the Prior Art It is, of course, commonplace to include a door operated switch in a laundry appliance so that as the door is opened operation of the machine stops. This type of machine, however, can be restarted with the door open merely by pushing the interlock switch which is usually accessible to the user from the front of the cabinet. Then, when the user attempts to redistribute the load in the basket or perform some other function, there is a real danger of injury due to the fact that the machine has been rendered fully operative by pushing the interlock switch. The problem becomes particularly troublesome in the case of combined washer-dryer machines where bums as well as damage from rotary elements can result.

In U. S. Pat. No. 2,843,239 there is described a safety device for washing machines employing a switch which is acmated by a solenoid operated locking or latching member. In U. S. Pat. No. 3,065,619 there is a disclosure of an automatic dry cleaning machine using a plurality of switches to sense the position of the door on the machine to prevent the door from being opened at any time during the complete dry cleaning cycle. In U. S. Pat. No. 3,408,834 there is disclosed a washing machine employing a door closure indicator member in combination with a lock member and a latch member for insuring that the door of the washing machine is closed during centrifugal extraction.

SUMMARY OF THE INVENTION The present invention provides a combination of mechanical latches and electrical circuitry associated with a hinged access door to prevent opening of the door as long as an energizing voltage is being applied to the main circuits of the machine. Specifically, the control of the present invention is used in conjunction with an on-off switch which is associated with a timer which puts the machine through a programmed sequence of operation. A switch is positioned at the access door and is closed by closure and latching of the door, this switch being in electrical series with the on-off switch associated with the timer. In the preferred form of the present invention, the circuitry includes a momentarily engageable start switch in series with the two aforementioned switches. Actuation of a door lock positioned to lock the access door against opening is under the control of a solenoid whose energizing coil is in series with the aforementioned switches. The door lock also operates a switch upon engagement of the door lock with the door in locking relation to provide a holding circuit about the momentarily engageable push-to-start switch.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantages of the invention will be readily apparent from the following description of certain preferred embodiments thereof, taken in conjunction with the accompanying drawings, although variations and modifications may be effected without departing from the spirit and scope of the novel concepts of the disclosure, and in which:

FIG. 1 is a front elevational view, partially broken away, of a combination washer-dryer machine employing the improvements of the present invention;

FIG. 2 is a front elevational view of the door-latching and door-locking assembly which is employed in conjunction with the assembly shown in FIG. 1;

FIG. 3 is a side elevational view of the assembly shown in FIG. 2, with the door lock being engaged with the top of the access door;

FIG. 4 is a fragmentary cross-sectional view similar to FIG. 3 but illustrating the mechanism in the unlatched condition; and

FIG. 5 is a circuit diagram of the interlock system of the type employed in the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 10 indicates generally a combination washer-dryer but it will be understood that the improvements of the present invention can be used to advantage in automatic washing and automatic drying assemblies individually. The washer-dryer assembly includes a cabinet 11 having an access door 12 at its front, the door 12 being hingedly secured at its bottom by means of spaced hinges l3 and 14. A handle 15 is provided along the upper rim of the door 12 to open and close the door in loading and unloading the machine.

The switch mechanisms which are instrumental in latching and locking the door are contained in a switch assembly generally indicated at reference numeral 16 of the drawings. Further details of the switch assembly 16 will be found in FIGS. 2 to 4, inclusive, of the drawings. As seen in FIG. 2, the switch assembly 16 includes a support 17 composed of synthetic resin or the like. A switch 18 having an operating button 19 is secured to the support 17 at the upper end thereof, and a second switch 20 having an operating button 21 is secured at the lower end of the support 17.

The switch 18 is of the normally closed type but is held in the open condition by the action of a plunger 22 and a compression spring 23 acting on the plunger 22 to depress the operating button 19. The spring 23 acts against a ferrule 24 to which is secured a flexible wire 25 which is trained around a roller 26 and has its opposite end secured to an armature 27 actuated by a solenoid 28 (FIG. 1).

As best seen in FIG. 2, the lower end of the plunger 22 has a rounded end portion 29 which is guided for vertical movement within an extension 30 of the support 17, the extension 30 having a rounded camming surface 31 which provides a keeper for the door latching mechanism.

A generally rectangular-shaped switch actuator or slide 32 is slidably mounted within an extension 33 of the support 17. Movement of the slide 32 in a vertical position acts against a flexible spring arm 34 which operates the operating button 21 of the switch 20.

The door handle mechanism 15 includes a forwardly inclined flange 35 and carries a pin 36 about which a latch member 37 is arranged to pivot. The latch 37 carries a hook portion 38 at its extreme end, the hook portion being biased by means of a spring (not shown) to engage the bottom of the slide 32 when the door is closed and thereby operate the operating button 21 through the flexible arm 34. In the closed door position, the hook portion 38 is received behind the keeper 30 as illustrated in FIG. 3.

The latch member 37 has an aperture 39 therein sufficiently large to receive the rounded head 29 of the plunger 22 therethrough as illustrated in FIG. 3. Thus, the engagement of the plunger through the aperture 39 provides a positive lock preventing opening of the door even when the hook portion 38 is pivoted in a position in which it is free of the keeper 30. It is only when the solenoid 28 is deenergized, thereby permitting the plunger 22 to be retracted by the action of the spring 23 that the door can be opened.

Turning now to the circuit diagram of FIG. 5, reference numerals 41 and 42 have been applied to the terminals which supply alternating current energy to the various components of this system. A switch 43 is included as a safety device, the switch 43 being normally closed but opening when there is an excessive amount of vibration of the machine. Such vibration sensitive switches are well known in the art and do not form a part of the present invention.

In the particular washer-dryer combination being described, a wash master switch 44 and a dry master switch 45 are in parallel relationship, the two switches being operated by means of the timer mechanism. A wash only switch is in series with the switch 45 and is normally closed. This switch is opened manually by an operator when only a wash cycle is desired.

The wash master switch 44 and the dry master switch 45 are closed only when the machine is in the process of carrying out a program, and both switches are open at the completion of a cycle. Thus, power will be supplied to the remainder of the circuits only when the timer is in a position corresponding to some part of a machine cycle.

To start the machine, the timer must be set to some cycle to close the wash master switch 44 or the dry master switch 45 and a push-pull switch 47 operated by axial movement of the timer shaft must be closed. When the door is closed and latched, the hook portion 37 pushes the operating button 21 of switch through the flexible arm 34, thereby closing switch 20. Then, by momentarily depressing a push-to-start switch 48, energizing voltage is available to the machine elements at a line 49. At this time, also, solenoid 28 is energized, thereby closing the switch 18 since the plunger 22 is then free of the operating button 19. The plunger moves into engagement with the aperture 38 and thereby provides a positive lock against opening the door, as well as providing a holding circuit to keep the elements energized when the push-to-start switch 48 is released. The door is thus completely locked, and may be unlocked by rotating the timer to a point where the wash master switch 44 and the dry master switch 45 are open or by axial movement of the timer shaft to open switch 47. Either of these two actions removes power from the entire machine. When this happens, solenoid 28 is deenergized and the spring 23 again retracts the plunger 22 causing operating button 19 of switch 18 to be pushed in, and permitting the door to be unlatched as shown in FIG. 4.

With the switch assembly of the present invention, the appliance is locked at all times when energized in a cycle. Furthermore, the machine cannot be started and will not operate unless the door is completely closed and latched. The door cannot be opened unless power is removed from the machine. The entire mechanism is readily installed in conjunction with a standard hinged door, and provides easy alignment and removal.

The positive lock provided by this system cannot easily be defeated by the operator. It thus provides a safety feature not heretofore present in machines of this type.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a laundry appliance including a timer arranged to control said appliance through a predetermined sequence of operations, and a hinged access door, a latch and interlock assembly comprising:

1. an on-ofi' switch associated with said timer;

2. a switch actuated by closure and latching of said door and being in series with said on-ofi switch (1) for allowing said appliance to be energized only when said door is latched;

3. a momentarily engageable start switch in series with switches (l) and (2);

4. a solenoid having its energizing coil in series with switchs 5. a door locking assembly arranged to lock said door against opening, said locking assembly being operable upon energization of said coil, and a door lock switch operable upon operation of said. door locking assembly, said door lock switch being in parallel with the series connected switches (2) and (3), thereby providing a bypass circuit for supplying power to said appliance when said momentary start switch is disengaged.

2. The laundry appliance of claim 1 in which said door locking assembly includes a plunger maintaining said door lock switch in open condition when said solenoid coil is deenergized.

3. The laundry appliance of claim 1 which includes support means mounting switch (2), said door latch switch, and said door latch.

4. In a laundry appliance including a timer arranged to control said appliance through a predetermined sequence of operations, and a hinged access door, a latch and interlock assembly comprising:

a door lock plunger mounted for longitudinal movement within said support,

a spring acting on said plunger to hold said plunger retracted,

a first switch actuated by one end of said plunger in its retracted position thereby providing a switched connection whose state is dependent on the position of the door lock,

means for operating said plunger to a locking position when said appliance is in operation,

a door latching member carried by said door, said latching member having a hook portion which engages a portion of said support when said door is in a latched position,

a second switch carried by said support, and

means operable by movement of said door latching member to operate said second switch when said door is latched.

5. The switch assembly of claim 4 which includes a flexible wire connecting said plunger with said plunger operating means.

6. The switch assembly of claim 4 in which said last-named means includes a flexible arm and a slidable switch actuator arranged to operate said normally open switch. 

1. In a laundry appliance including a timer arranged to control said appliance through a predetermined sequence of operations, and a hinged access door, a latch and interlock assembly comprising:
 1. an on-off switch associated with said timer;
 2. a switch actuated by closure and latching of said door and being in series with said on-off switch (1) for allowing said appliance to be energized only when said door is latched;
 3. a momentarily engageable start switch in series with switches (1) And (2);
 4. a solenoid having its energizing coil in series with switchs (1), (2) and (3);
 5. a door locking assembly arranged to lock said door against opening, said locking assembly being operable upon energization of said coil, and a door lock switch operable upon operation of said door locking assembly, said door lock switch being in parallel with the series connected switches (2) and (3), thereby providing a bypass circuit for supplying power to said appliance when said momentary start switch is disengaged.
 2. a switch actuated by closure and latching of said door and being in series with said on-off switch (1) for allowing said appliance to be energized only when said door is latched;
 2. The laundry appliance of claim 1 in which said door locking assembly includes a plunger maintaining said door lock switch in open condition when said solenoid coil is deenergized.
 3. The laundry appliance of claim 1 which includes support means mounting switch (2), said door latch switch, and said door latch.
 3. a momentarily engageable start switch in series with switches (1) And (2);
 4. a solenoid having its energizing coil in series with switchs (1), (2) and (3);
 4. In a laundry appliance including a timer arranged to control said appliance through a predetermined sequence of operations, and a hinged access door, a latch and interlock assembly comprising: a door lock plunger mounted for longitudinal movement within said support, a spring acting on said plunger to hold said plunger retracted, a first switch actuated by one end of said plunger in its retracted position thereby providing a switched connection whose state is dependent on the position of the door lock, means for operating said plunger to a locking position when said appliance is in operation, a door latching member carried by said door, said latching member having a hook portion which engages a portion of said support when said door is in a latched position, a second switch carried by said support, and means operable by movement of said door latching member to operate said second switch when said door is latched.
 5. The switch assembly of claim 4 which includes a flexible wire connecting said plunger with said plunger operating means.
 5. a door locking assembly arranged to lock said door against opening, said locking assembly being operable upon energization of said coil, and a door lock switch operable upon operation of said door locking assembly, said door lock switch being in parallel with the series connected switches (2) and (3), thereby providing a bypass circuit for supplying power to said appliance when said momentary start switch is disengaged.
 6. The switch assembly of claim 4 in which said last-named means includes a flexible arm and a slidable switch actuator arranged to operate said normally open switch. 